relnote: Reduce the size of QUIC's TransmissionInfo struct based on

net/quic/quic_protocol.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_QUIC_QUIC_PROTOCOL_H_
 #define NET_QUIC_QUIC_PROTOCOL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 #include <limits>
@@ skipping 33 matching lines @@
 typedef uint64 QuicPublicResetNonceProof;
 typedef uint8 QuicPacketEntropyHash;
 typedef uint32 QuicHeaderId;
 // QuicTag is the type of a tag in the wire protocol.
 typedef uint32 QuicTag;
 typedef std::vector<QuicTag> QuicTagVector;
 typedef std::map<QuicTag, std::string> QuicTagValueMap;
 // TODO(rtenneti): Didn't use SpdyPriority because SpdyPriority is uint8 and
 // QuicPriority is uint32. Use SpdyPriority when we change the QUIC_VERSION.
 typedef uint32 QuicPriority;
+typedef uint16 QuicPacketLength;
 
 // Default initial maximum size in bytes of a QUIC packet.
 const QuicByteCount kDefaultMaxPacketSize = 1350;
 // Default initial maximum size in bytes of a QUIC packet for servers.
 const QuicByteCount kDefaultServerMaxPacketSize = 1000;
 // The maximum packet size of any QUIC packet, based on ethernet's max size,
 // minus the IP and UDP headers. IPv6 has a 40 byte header, UPD adds an
 // additional 8 bytes.  This is a total overhead of 48 bytes.  Ethernet's
 // max packet size is 1500 bytes,  1500 - 48 = 1452.
 const QuicByteCount kMaxPacketSize = 1452;
@@ skipping 1113 matching lines @@
 struct NET_EXPORT_PRIVATE TransmissionInfo {
   // Used by STL when assigning into a map.
   TransmissionInfo();
 
   // Constructs a Transmission with a new all_tranmissions set
   // containing |packet_number|.
   TransmissionInfo(RetransmittableFrames* retransmittable_frames,
                    QuicPacketNumberLength packet_number_length,
                    TransmissionType transmission_type,
                    QuicTime sent_time,
-                   QuicByteCount bytes_sent,
+                   QuicPacketLength bytes_sent,
                    bool is_fec_packet);
 
   RetransmittableFrames* retransmittable_frames;
   QuicPacketNumberLength packet_number_length;
+  QuicPacketLength bytes_sent;
+  uint16 nack_count;
   QuicTime sent_time;
-  QuicByteCount bytes_sent;
-  QuicPacketCount nack_count;
   // Reason why this packet was transmitted.
   TransmissionType transmission_type;
-  // Stores the packet numbers of all transmissions of this packet.
-  // Must always be nullptr or have multiple elements.
-  PacketNumberList* all_transmissions;
   // In flight packets have not been abandoned or lost.
   bool in_flight;
   // True if the packet can never be acked, so it can be removed.
   bool is_unackable;
   // True if the packet is an FEC packet.
   bool is_fec_packet;
+  // Stores the packet numbers of all transmissions of this packet.
+  // Must always be nullptr or have multiple elements.
+  PacketNumberList* all_transmissions;
 };
 
 // Convenience wrapper to wrap an iovec array and the total length, which must
 // be less than or equal to the actual total length of the iovecs.
 struct NET_EXPORT_PRIVATE QuicIOVector {
   QuicIOVector(const struct iovec* iov, int iov_count, size_t total_length)
       : iov(iov), iov_count(iov_count), total_length(total_length) {}
 
   const struct iovec* iov;
   const int iov_count;
   const size_t total_length;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_PROTOCOL_H_